Ascidian spicules

Classification: ntax_non_cocco -> Ascidian spicules
Sister taxa: Haptophytes, Parmales, Silicoflagellates, scales and miscellaneous, Dinophytes, Diatoms, Zooplankton groups, Ascidian spicules, Crystals and crud, Palaeozoic nannofossils, hidden

Distinguishing features: Typically spherically-radiate calcite bodies, formed of largish tapering, radiate elements with radial c-axes. Larger and less regularly-shaped than typical nannofossils.

Daughter taxa (time control age-window is: 0-800Ma)Granddaughter taxa
V or horseshoe shaped nannolith showing high birefringence and c-axis parallel to length of nannolith



Citation: Ascidian spicules
Rank: Order
Synonyms: Fossil taxa which are probably based on ascidian spicules include the following [all based on my interpretation unless otherwise noted JRY]
Taxonomic discussion: Ascidians (common name sea squirts) are benthic tunicates, so nothing really to do with nannoplankton. However, the spicules they produce commonly occur in nannoplankton preparations, especially from shallow marine environments. So, nannoplankton workers need to be able to recognise them. Varol & Houghton (1996) provide a useful overview for nannofossil specialists and also propose Linnean names for varous different morphotypes. Varol (2006) developed this approach further, proposing names for many different Mesozoic morphotypes. Lukowiak et al. (2016) record fossil specimens from the Miocene and give modern references.

Catalog entries: Discoaster athanasiui * , Discoaster irregularis * , Discoaster mrazeci * , Discoaster multinucleatus * , Discoaster olteniae * , Discoaster pentaradiatus communis * , Discoaster pentaradiatus flosculoides * , Discoaster sabbae * , Discoaster slatiorensis * , Gongylis * , Gongylis salzwedelensia * , Heliodiscoaster cayeuxi * , Heliodiscoaster cernaensis * , Heliodiscoaster concentricus * , Heliodiscoaster deflandrei * , Heliodiscoaster irregularis * , Heliodiscoaster rumanus * , Hemidiscoaster triradiatus aquitanicus * , Micrascidites [no catalog entry yet], Micrascidites vulgaris [no catalog entry yet], Perforocalcinella * , Perforocalcinella fusiformis * , Perforocalcinella petali * , Tansinius * , Tansinius angularis * , Tansinius irregularis * , Tansinius olteniae * , Tansinius rectangularis * , Tansinius stefanescui *

Distinguishing features: Typically spherically-radiate calcite bodies, formed of largish tapering, radiate elements with radial c-axes. Larger and less regularly-shaped than typical nannofossils.

Geological Range:
Last occurrence (top): Extant Data source:
First occurrence (base): within Jurassic Period (145.01-201.30Ma, base in Hettangian stage). Data source:


Bona, J. (1964). Coccolithophorida-vizsgalatok a meceski retegekben (Coccolithopohriden-Unntersuchungen in der neogen Schichtenfolge des Meeskggerbirges). Földtani Közlöny - Bulletin of the Hungarian Geological Society. 94: 121-131. gs

Bown, P. R. (2005d). Palaeogene calcareous nannofossils from the Kilwa and Lindi areas of coastal Tanzania (Tanzania Drilling Project 2003-4). Journal of Nannoplankton Research. 27(1): 21-95. gs V O

Bown, P. R. (2010). Calcareous nannofossils from the Paleocene/Eocene Thermal Maximum interval of southern Tanzania (TDP Site 14). Journal of Nannoplankton Research. 31(1): 11-38. gs V O

Deflandre, G. & Deflandre-Rigaud, M. (1956). Micrascidites manip. nov., sclerites de Didemnides (Ascidies, Tuniciers) fossiles due Lutétian du Bassin Parisien et du Balcombien d'Australia. Compte Rendu Sommaire des Séances de la Société Géologique de France. 1956: 47-48. gs

Filipescu, M. & Hanganu, E. (1960). Sur les Discoastérides du Tertiare du N-O de l'Olténie. Revue Roumaine de Géologie Géophysique et Géographie, Serie de Géologie. 4(2): 217-232. gs

Hoffmann, N. (1970c). Taxonomische Untersuchungen an Coccolithen aus der Kreide Norddeutchlands anhand elektronenmikroskopischer Aufnamen. Hercynia. 7(1-3): 163-198. gs V O

Lukowiak, M., Dumitriu, S. & Ionesi, V. (2016). First fossil record of early Sarmatian didemnid ascidian spicules (Tunicata) from Moldova. Geobios. 49: 201-209. gs

Menini, A., Mattioli, E., Spangenberg, J. E., Pittet, B. & Suan, G. (2018). New calcareous nannofossil and carbon isotope data for the Pliensbachian/Toarcian boundary (Early Jurassic) in the western Tethys and their paleoenvironmental implications. Newsletters on Stratigraphy. -. gs

Varol, O. & Houghton, S. D. (1996). A review and classification of fossil didemnid ascidian spicules. Journal of Micropalaeontology. 15: 135-149. gs V O

Varol, O. (2006). Didemnid ascidian spicules from the Arabian Peninsula. Journal of Nannoplankton Research. 28(1): 35-56. gs V O

Young, J. R. (1998). Neogene. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series. 225-265. gs V O


Ascidian spicules compiled by Jeremy R. Young viewed: 20-6-2021

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Comments (2)

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magdalena lukowiak (Warsaw, Poland)
Thanks guys for such a possitive reactions to our latest paper! :) we are glad that you liked it. If you are interested in fossil ascidian spicules, I also recommend my article from 2012: _ukowiak, M. 2012. First Record of Late Eocene Ascidians (Ascidiacea, Tunicata) from Southeastern Australia: Journal of Paleontology 86 (3): 521–526
If any of you want a pdf of this paper, please, do not hesitate to write to me. Cheers!
Ines Galovic (Croatian Geological Survey, Croatia)
Very nice article about ascidian spicules at Researchgate published in April 2016 in Geobios. Unfortunatelly I couldn't add a link here. :(
Jeremy Young (UCL, UK)
thanks for the tip - I just found it and and yes it is a nice paper , i will add mention of it on the page as it has modern references etc.

Lukowiak, M.; Dumitriu, S. & Ionesi, V., (2016). First fossil record of early Sarmatian didemnid ascidian spicules (Tunicata) from Moldova. Geobios, 49: 201-209.
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